\documentclass[a4paper]{article}

\usepackage{pgfplots}
\usepackage[top=1cm,bottom=1cm]{geometry}
\usepgfplotslibrary{patchplots}

\begin{document}
\parindent=0pt
\parskip=10pt

\pgfplotsset{ticklabel style={overlay}}
\def\plots{%
	%\addplot3 [mark=cube, mark size=2cm] coordinates {(0,0,0)};
	\addplot {x^2};
}%
%\tracingcommands=2\tracingmacros=2

Case $W < H$ (default config)

\fbox{\texttt{\strut scale mode=stretch to fill}}
\fbox{\texttt{\strut scale uniformly strategy=change horizontal limits}}

\fbox{\texttt{\strut scale mode=stretch to fill}}
\fbox{\texttt{\strut scale uniformly strategy=change vertical limits}}

\fbox{\texttt{\strut scale mode=stretch to fill}}
\fbox{\texttt{\strut scale uniformly strategy=auto}}

\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	%scale mode=scale uniformly,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}%
}%
\message{NEUES BILD^^J^^J^^J}
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	scale mode=scale uniformly,
	scale uniformly strategy=change horizontal limits,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}%
}

\message{NEUES EXPERIMENT^^J^^J^^J}
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	%scale mode=scale uniformly,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}}%
\message{NEUES BILD^^J^^J^^J}
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	scale mode=scale uniformly,
	scale uniformly strategy=change vertical limits,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}%
}

\message{NEUES EXPERIMENT^^J^^J^^J}
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	%scale mode=scale uniformly,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}}%
\message{NEUES BILD^^J^^J^^J}
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
	%axis equal=true, 
	scale mode=scale uniformly,
	scale uniformly strategy=auto,
	%axis lines=none, 
	]
	\plots
	\end{axis}
	\end{tikzpicture}%
}
\end{document}

